Comment on glycated hemoglobin level after emergency COVID-19.

Dear Editor, we would like to share our ideas on the publication “Unexpected decline in glycated hemoglobin level after emergency COVID‐19 measures in three robust older Japanese women with prediabetes/mild type‐2 diabetes.” It is possible that COVID‐19 might affect metabolism in the elderly. The alteration of hemoglobin A1C in COVID‐19 has been reported since the first outbreak of the disease in Southeast Asia. The monitoring of glycated hemoglobin in the current study is interesting. It is necessary to recheck for laboratory quality control and the same set of analyzers should be used in the serial analysis. According to a recent report, the total error ranged from 2.87% to 4.75% using fingerstick samples and from 2.93% to 3.80% using venous samples. Therefore, changes in hemoglobin A1C levels might be associated with imprecision of the test. Another concern is about laboratory interference. During the disease process of COVID‐19, the inflammatory/immune response results in a high blood viscosity and there might be an increased concentration of blood parameters. However, after COVID‐19 recovery, the postinfection laboratory parameters might return to normal after blood viscosity returns to a normal level.

Disclosure statement

The authors declare no conflict of interest.